Pump device for ice cream or yogurt machine

ABSTRACT

A pump device for a frozen product machine includes a pump casing, first and second rotor gear, and a sealing arrangement. The first and second rotor gears fit in a pumping cavity of the pump casing in a rotatably movable manner that creates a suction effect for pumping and mixing liquid mixture with air to produce a mixture product. The sealing arrangement includes a plurality of sealing elements provided between two outer side surfaces of the first and second rotor gears and inner side surfaces of the pump casing for ensuring the liquid mixture and air being sealed and mixed within the pumping cavity through the first and second rotor gears and for preventing the first and second rotor gears from being direct-surface contact of the pump casing.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to a pump device, and more particularly to a pump device for a yogurt or ice-cream machine which is capable of preventing mixture leakage while allowing convenient cleaning of the pump device.

2. Description of Related Arts

A conventional pump for feeding liquid mixture for ice-cream or yogurt usually comprises a casing having a liquid inlet, an air inlet and a mixture outlet, and a plurality of intermeshing rotors, received in the casing to connect the liquid inlet, the air inlet and the mixture outlet. In particular, the intermeshing rotors are connected with each other to define a first chamber and a second chamber such that when one of the intermeshing rotors is rotated, another intermeshing rotor is driven to rotate to create a suction effect from the first chamber to the second chamber.

Conventionally, liquid and air enter the pump through the liquid inlet and air inlet respectively into the first chamber, wherein the liquid and air mix in the pump to form mixture which is then pumped out of the second chamber to feed an ice-cream or yogurt machine for making ice-cream or yogurt. There are several disadvantages regarding this conventional pump.

First, the rotors of the conventional pump are usually gears which must intermesh with each other in a very precise manner for facilitating effective mixing of liquid and air and for accomplishing efficient operation of the pump. As a result, each of the components of the pump, and especially the rotors, must be made very precise in order to allow each of the components to fit with each other for creating a suction effect between the first and second chambers and for effectively and efficiently making ice-cream or yogurt. All these requirements account for the very expensive manufacturing cost and their ultimate selling price of conventional pumps for ice-cream and yogurt machines.

Second, since the components of the conventional pumps must be very precise, it is very difficult for users of conventional pumps to disassemble and reassemble the pump for cleaning. As a matter of fact, since the pump is primarily used for pumping liquid having a relatively high viscosity, it needs cleaning regularly. However, the pump is usually mounted adjacent to the ice-cream or yogurt machine and should be connected to a tank or storage device for storing the liquid. The result is that it is very difficult for a user to detach the pump from other devices (such as the ice-cream machine) for cleaning. Likewise, it is very difficult or at least very inconvenient for the user to reassemble the pump and reattach it with other machines or devices.

Furthermore, when the components of the pump are made to be very precise, it is very difficult for users of the pump to reassemble the pump with the same precision as tough the pump was not disassembled. When the pump is not reassembled properly, the performance of the pump will be deteriorated and this in turn affects the quality or the efficiency of the ice-cream or yogurt produced.

In addition, since the casing is made of stainless steel, the intermeshing rotors must be made of different materials such as alloy. Accordingly, in order to provide a sealing effect between the first and second chambers, two side surfaces of each of the intermeshing rotors must be engaged with the two inner surfaces of the casing respectively such that the intermeshing rotors are engaged with the casing in a surface-to-surface contacting engagement to ensure the sealing effect between the first and second chambers. Otherwise, the mixture of liquid and air will leak to the second mixture through a clearance between the side surface of the intermeshing rotor and the inner surface of the casing. In other words, if the intermeshing rotor is made of stainless steel, which is the same material of the casing, heat will be substantially generated by the friction between the side surface of the intermeshing rotor and the inner surface of the casing when the intermeshing rotor is rotated. The heat will affect the quality of the ice-cream or yogurt.

In other words, the intermeshing rotors must be made of different materials such as alloy. When the teeth of the intermeshing rotors are meshed with each other to transmit the rotational power from one to another, the teeth of the intermeshing rotors are gradually torn, especially the teeth being precisely meshed. It is known that the durability of stainless steel is better than that of alloy. When the intermeshing rotors are made of stainless, the service life span of the intermeshing rotors will be substantially prolonged. However, it is impossible to incorporate the stainless steel made intermeshing rotors with stainless steel casing because of the extreme high heat generation as it is mentioned above.

Furthermore, the torn intermeshing rotors must be replaced every three months when the intermeshing rotors are made of alloy. Most importantly, the alloy residues of torn intermeshing rotors will mix with the ice-cream or yogurt through the suction effect of the pump from the first chamber to the second chamber. Therefore, the conventional pump for feeding liquid mixture for ice-cream or yogurt requires relatively high maintenance cost and creates harmful substance to our health.

SUMMARY OF THE PRESENT INVENTION

The invention is advantageous in that it provides a pump device for a frozen product machine, especially for a milk-frozen product such as yogurt or ice-cream machine, which is capable of preventing mixture leakage while allowing convenient cleaning of the pump device.

Another advantage of the invention is to provide a pump device for a frozen product machine, wherein the sealing arrangement is provided between two outer side surfaces of the rotor gears and two inner side surfaces of the pump casing. Therefore, the sealing arrangement not only provides a sealing effect for ensuring the liquid mixture and air being sealed and mixed within the pumping cavity through the rotor gears but also forms a partition for preventing the rotor gears from being direct-surface contact of the pump casing.

Another advantage of the invention is to provide a pump device for a frozen product machine, wherein no substantial heat is generated due to the friction between the rotor gears and the pump casing.

Another advantage of the invention is to provide a pump device for a frozen product machine, wherein the rotor gears and said pump casing are made of stainless steel to enhance the durability of the pump device so as to enhance the service life span thereof and to minimize any unwanted residue being formed when the rotor gears are gradually worn.

Another advantage of the invention is to provide a pump device for a frozen product machine, which facilitates easy and convenient assembling or disassembling of the pump casing.

Another advantage of the invention is to provide a pump device for a frozen product machine, wherein the components of the pump device can be made with less precision without jeopardizing the overall quality of the ice-cream or yogurt as compared to conventional pump devices. In other words, the manufacturing cost of the present invention can be minimized without affecting its performance.

Another advantage of the invention is to provide a pump device for a frozen product machine, which does not involve complicated or expensive mechanical components so as to minimize the manufacturing cost of the present invention.

Another advantage of the invention is to provide a pump device for a frozen product machine, wherein no expensive or complicate mechanical structure is required to employ in the present invention in order to achieve the above mentioned objects. Therefore, the present invention successfully provides an economic and efficient solution for providing a sealing effect within the pumping cavity for preventing direct surface contact between the rotor gears and the pump casing.

Additional advantages and features of the invention will become apparent from the description which follows, and may be realized by means of the instrumentalities and combinations particular point out in the appended claims.

According to the present invention, the foregoing and other objects and advantages are attained by providing a pump device for a frozen product machine, which comprises a pump casing, a plurality of rotor gears, and a sealing arrangement.

The pump casing has two inner side surfaces, a pumping cavity between the two inner side surfaces, a liquid inlet communicating the pumping cavity with an exterior of the pump device for allowing liquid mixture to be pumped into the pumping cavity through the liquid inlet, an air inlet communicating the pumping cavity for allowing intake of air through the air inlet to mix with the liquid mixture in the pumping cavity, and a mixture outlet communicated with the frozen product machine.

The rotor gears are fitted in the pumping cavity in a rotatably movable manner, wherein the rotor gears are driven to rotated to create a suction effect for pumping and mixing the liquid mixture with the air from the liquid inlet and the air inlet respectively to the mixture outlet so as to produce a mixture product.

The sealing arrangement comprises a plurality of sealing elements provided between two outer side surfaces of the rotor gears and the inner side surfaces of the pump casing for ensuring the liquid mixture and the air being sealed and mixed within the pumping cavity through the rotor gears and for preventing the rotor gears from being direct-surface contact of the pump casing.

In accordance with another aspect of the invention, the present invention comprises a method of making frozen product, comprising the following steps.

(1) Feed a liquid mixture and air into a pumping cavity of a pump casing through a liquid inlet and an air inlet thereof respectively.

(2) Drive two gear rotors to rotate within the pump casing for generating a suction effect to pump and mix the liquid mixture with the air to form a mixture product.

(3) Provide a sealing effect between two outer side surfaces of the rotor gears and two inner side surfaces of the pump casing by a sealing arrangement for ensuring the liquid mixture and the air being sealed and mixed within the pumping cavity through the rotor gears and for preventing the rotor gears from being direct-surface contact of the pump casing.

(4) Pump out the mixture product out of the pumping cavity through a mixture outlet of the pump casing.

Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.

These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ice-cream or yogurt machine with a pump device according to a preferred embodiment of the present invention.

FIG. 2 is a perspective view of the pump device for an ice-cream or yogurt machine according to the above preferred embodiment of the present invention.

FIG. 3 is an exploded perspective view of the pump device for an ice-cream or yogurt machine according to the above preferred embodiment of the present invention.

FIG. 4 is a side sectional view of the pump device for an ice-cream or yogurt machine according to the above preferred embodiment of the present invention.

FIG. 5 is a top sectional view of the pump device for an ice-cream or yogurt machine according to the above preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 to FIG. 5 of the drawings, a pump device for a frozen product machine 80, such as a yogurt machine or an ice-cream machine, according to a preferred embodiment of the present invention is illustrated, in which the pump device is embodied as a gear pump for the feeding and mixing of liquid and air for the formation of liquid and air emulsions as a mixture product. Accordingly, the pump device of the present invention comprises a pump casing 10, a plurality of rotor gears 20, 30, and a sealing arrangement 40.

The pump casing 10 has two inner side surfaces 101 and a pumping cavity 16 defined between the two inner side surfaces 101. The pump casing 10 further has a liquid inlet 13 communicating the pumping cavity 16, an air inlet 14 communicating the pumping cavity 16, and a mixture outlet 15 communicating the pumping cavity 16 with the frozen product machine 80.

According to the preferred embodiment, the pump device is embodied as a two-gear pump to define first and second rotor gears 20, 30 fitted in the pumping cavity 16 of the pump casing 10 in a rotatably movable manner, wherein the first and second rotor gears 20, 30 are driven to rotated to create a suction effect for pumping the mixing the liquid mixture with the air from the liquid inlet 13 and the air inlet 14 respectively to the mixture outlet 15 so as to produce the frozen product.

The sealing arrangement 40 comprises a plurality of sealing elements 41 provided between two outer side surfaces of the first and second rotor gears 20, 30 and the inner side surfaces 101 of the pump casing 10 for ensuring the liquid mixture and the air being sealed and mixed within the pumping cavity 16 through the first and second rotor gears 20, 30 and for preventing the first and second rotor gears 20, 30 from being direct-surface contact of the pump casing 10.

According to the preferred embodiment of the present invention, the pump device is for pumping raw material for yogurt or ice-cream in liquid form, mix it with air and deliver it to the yogurt or ice-cream device. The pump is therefore connected between a storage tank 70 and the yogurt or ice-cream machine 80.

Accordingly, the liquid mixture is fed into the pumping cavity 16 through the liquid inlet 13, wherein the liquid inlet 13 is formed at the pump casing 10 as a through communication channel communicating the pumping cavity 16 with an exterior of the pump device for allowing the liquid mixture to be pumped into the pumping cavity 16 through the liquid inlet 13. In other words, the liquid inlet 13 communicates the pumping cavity 16 with an exterior of the pump device for allowing liquid mixture, such as raw materials for making the yogurt or ice-cream, to be pumped from the storage tank 70 into the pumping cavity 16 through the liquid inlet 13.

The air inlet 14 is formed at the pump casing 10 for allowing intake of air through the air inlet 14 to mix with the liquid mixture in the pumping cavity 16. Once the liquid mixture is mixed with the air within the pumping cavity 16, the mixture product is produced and is delivered out of the pumping cavity 16 through the mixture outlet 15 to the frozen product machine 80 for whipping process.

According to the preferred embodiment, the pump casing 10 comprises a first casing member 11, a second casing member 12 detachably coupled with the first casing member 11 to form the pumping cavity 16 within the first and second casing members 11, 12. Accordingly, the two inner side surfaces 101 of the pump casing 10 form at the first and second casing members 11, 12 respectively.

The pump casing 10 further comprises a plurality of fastening assemblies 17 operatively provided on the pump casing 10 for selectively fastening the first and second casing member 11, 12. As shown in FIG. 3 of the drawings, each of the fastening assemblies 17 contains a plurality of fastening holes 171 spacedly formed at the second casing member 12, a plurality of elongated threaded heads 173 spacedly extended from the first casing member 11 to alignedly extend through the fastening holes 171 respectively, and a plurality of threaded fastening knobs 172 operatively fastened to the threaded heads 173 after the threaded heads 173 extended through the fastening holes 171 for detachably fastening the corresponding portions of the first and the second casing member 11, 12. Note that the fastening assemblies 17 are provided at two side portions of the first and the second casing member 11, 12 so that each fastening assembly 17 is arranged to fasten the correspond side portions of the first and the second casing member 11, 12.

As shown in FIG. 5, the liquid inlet 13 is formed at bottom side of the pump casing 10. Preferably, the liquid inlet 13 is formed at the second casing member 12 of the pump casing 10. The liquid inlet 13 is connected to the storage tank 70 via a feeding tube 71, wherein the liquid mixture for making the ice-cream or yogurt is pumped into the pumping cavity 16 via the feeding tube 71 and the liquid inlet 13.

As shown in FIG. 3, the feeding tube 71 has a feeding end rotatably coupled at the liquid inlet 13, wherein a plurality of feeding holes 711 are spacedly formed at the feeding end of the feeding tube 71. The feeding holes 711 are formed with different diameters for selectively controlling the amount of the liquid mixture being fed into the pumping cavity 16, such that when the feeding tube 71 is adjustably rotated at a position that the pumping cavity 16 is alignedly communicated with one of the feeding holes 711, the liquid mixture is fed into the pumping cavity 16 via the corresponding feeding holes 711.

The air inlet 14 is formed at the front side of the pump casing 10 at a bottom portion thereof. Preferably, the air inlet 14 is formed at the second casing member 12 of the pump casing 10.

The mixture outlet 15 is formed at the front side of the pump casing 10 at an upper portion thereof. Preferably, the mixture outlet 15 is formed at the second casing member 12 of the pump casing 10.

The first and the second rotor gears 20, 30 are rotatably received in the pumping cavity 16 for creating a vacuum effect to suck liquid mixture and air through the liquid inlet 13 and the air inlet 14 into the pumping cavity 16. The first and the rotor gears 20, 30 also delivers pumping force to pump the mixture of the liquid mixture and the air out of the pumping cavity 16 through the mixture outlet 15.

Moreover, the pump casing 10 is communicated with a motor device 60 which is arranged to drive the rotor gears 20, 30 to rotate for sucking the liquid raw material and air into the pumping cavity 16, and creating a pumping force, i.e. the suction effect, to deliver the mixture product to the frozen product machine 80 for making the frozen product such as yogurt or ice-cream.

More specifically, the first rotor gear 20 has two outer side surfaces 201 and an outer circumferential edge portion between the two outer side surfaces 201. The first rotor gear 20 further comprises a plurality of first engaging teeth 21 peripherally formed along the outer circumferential edge portion of the first rotor gear 20.

The second rotor gear 30 has two outer side surfaces 301 and an outer circumferential edge portion between the two outer side surfaces 301. The second rotor gear 30 further comprises a plurality of second engaging teeth 31 peripherally formed along the outer circumferential edge portion of the second rotor gear 30, wherein the first engaging teeth 21 are meshed with the second engaging teeth 31 such that when the first gear rotor 20 is rotated, the second gear rotor 30 is driven to rotate. In other words, the first rotor gear 20 is the driving gear while the second rotor gear 30 is the driven gear. Thus, the first rotor gear 20 is connected to the motor device 60 which drives the first rotor gear 20 to rotate at a predetermined speed.

Thus, the pumping casing 10 further has a driving slot 18 formed on the first casing member 11, whereas the motor device 60 comprises a driving shaft 61 extended to connect with the first gear rotor 20 via the driving slot 18 so as to drive the first gear rotor 20 to rotate at a predetermined speed.

Thus, the first rotor gear 20 further has a first gear slot 22 formed at a mid-potion thereof, wherein the driving shaft 61 of the motor device 60 is arranged to connect to the first gear slot 22 through the driving slot 18 for driving the first rotor gear 20 to rotate. On the other hand, the second rotor gear 30 further has a second gear slot 32 whereas the pump casing 10 further comprises a supporting shaft 19 extended from the first casing member 11 to connect with the second gear slot 32, wherein the second rotor gear 30 is arranged to be driven to rotate by the first rotor gear 20 about the supporting shaft 19. The second rotor gear 30 further comprises an intermediate member 33 provided between the supporting shaft 19 and the outer circumferential edge portion 301 of the second rotor gear 30.

As shown in FIG. 5, the first rotor gear 20 are meshed with the second rotor gear 30 to define a first chamber 161 within the pumping cavity 16 to communicate with the liquid inlet 13 and a second chamber 162 within the pumping cavity 16 to communicate with the mixture outlet 15, wherein the pumping cavity 16 is sealed by the sealing arrangement 40 for ensuring the liquid mixture and air being mixed from the first chamber 161 to the second chamber 162 to form the mixture product.

Accordingly, when the first and second rotor gears 20, 30 are driven to rotate, the suction effect is created to feed the liquid mixture and air from the first chamber 161 to the second chamber 162. Therefore, the first and second chambers 161, 162 must be sealed tightly to ensure the leakage of the liquid mixture and air.

On the other hand, the pump casing 10 preferably has two air inlets 14 spacedly formed on the second casing member 12, wherein a predetermined amount of air is sucked into the pumping cavity 16 via the two air inlets 14 for mixing with the liquid mixture to form the mixture product which is to be delivered to the yogurt or ice-cream machine 80 through the mixture outlet 15.

Accordingly, the two air inlets 14 are formed at the bottom portion of the pump casing 10 to align with two bottom portions of the first and second gear rotors 20, 30 respectively, wherein the air is filled at the gaps between the engaging teeth 21, 31 of the first and second gear rotors 20, 30 such that the air will be delivered into the first chamber 161 during the rotational movements of the first and second gear rotors 20, 30.

As a result, the mixture outlet 15 is also formed on the second casing member 12 in such a manner that the mixture of liquid and air is to be delivered out of the pumping cavity 16 via the mixture outlet 15. A discharge tube 50 is connected between the mixture outlet 15 and the yogurt or ice-cream machine 80 for transporting the mixture from the pumping cavity 16 to the yogurt or ice-cream machine 80.

As it is mentioned above, the conventional design of the pump device is that the outer side surface 201, 301 of each of the first and second rotor gears 20, 30 must be tightly engaged with the corresponding inner side surface 101 of the pump casing 10 to prevent the leakage of the liquid mixture and air through the clearance between the outer side surfaces 201, 301 of the first and second rotor gears 20, 30 and the inner side surface 101 of the pump casing 10.

According to the preferred embodiment, the sealing arrangement 40 is provided at the clearance between the outer side surfaces 201, 301 of the first and second rotor gears 20, 30 and the inner side surface 101 of the pump casing 10. Therefore, the outer side surfaces 201, 301 of the first and second rotor gears 20, 30 will not contact with the inner side surface 101 of the pump casing 10 while sealing effect is provided at the clearance.

As shown in FIGS. 3 and 4, each of the sealing elements 41 is made of elastic material adapted to be deformed to fit between the outer side surface 201, 301 of each of the first and second rotor gears 20, 30 and the corresponding inner side surface 101 of the pump casing 10 so as to create the sealing effect therebetween while enabling each of the rotor gears 20, 30 being rotated within the pumping cavity 16.

Preferably, each of the sealing elements 41 is made of rubber material which is capable of preventing air and liquid from passing through the area sealed by the corresponding sealing elements 41.

As shown in FIGS. 3 and 4, each of the sealing elements 41 is embodied as a sealing ring retained at the outer side surface 201, 301 of each of the first and second rotor gears 20, 30 to bias against the corresponding inner side surface 101 of the pump casing 10. Therefore, the liquid mixture and air must pass from the first chamber 161 to the second chamber 162 through the meshing engagement between the first and second engaging teeth 21, 31 during the rotational movements of the first and second gear motors 20, 30. It is worth mentioning that the sealing elements 41 provide substantially complete sealing of the liquid mixture and the air so as to allow effective mixture of the air and the liquid within the pumping cavity 16 while facilitating easy and convenient disassembling and reassembling of the pump casing 10.

Thus, the sealing elements 41 are provided at the first and the second rotor gears 20, 30 respectively for preventing the air and the liquid sucked by the first and the second rotor gears 20, 30 from reaching the area sealed by the sealing elements 41 within the pumping cavity 16 (i.e. the central portion of each of the first and the second rotor gear 20, 30).

The sealing arrangement 40 further comprises a plurality of sealing slots 42 indent on the outer side surfaces 201, 301 of the first and second gear rotors 20, 30 respectively, wherein the sealing elements 41 are retained at the sealing slots 42 respectively to contact and seal with the inner side surfaces 101 of the pump casing 10.

Each of the sealing slots 42 is shaped corresponding to the respective sealing element 41, wherein when the sealing element 41 is disposed at the sealing slot 42, a portion of the sealing element 41 is received in the sealing slot 42 to retain the sealing element 41 in position while another portion of the sealing element 41 is protruded out of the outer side surfaces 201, 301 of the respective first and second gear rotors 20, 30 so as to bias against the respective inner side surface 101 of the pump casing 10.

Accordingly, each of the sealing elements 41 is embodied as a substantially circular sealing ring received in the sealing slots 42. Accordingly, each of the sealing slots 42 are also substantially circular in cross section which is arranged to fittedly accommodate the corresponding sealing element 41. Note that the sealing slot 42 at the second rotor gear 30 is formed at the boundary between the intermediate member 33 and the outer circumferential edge portion of the second rotor gear 30.

Since the sealing elements 41 are pressed between the outer side surface 201, 301 of each of the first and second rotor gears 20, 30 and the corresponding inner side surface 101 of the pump casing 10, the first and second rotor gears 20, 30 will not directly contact with the pump casing 10 in a surface-to-surface contacting manner. Therefore, there will be no heat generation by the friction between the outer side surfaces 201, 301 of the first and second rotor gears 20, 30 and the inner side surfaces 101 of the pump casing 10 during the rotational movements of the first and second gear motors 20, 30.

After solving the unwanted heat generated problem, all the pump casing 10, and the first and second rotor gears 20, 30 can be made of stainless steel. When both the first and second rotor gears 20, 30 are made of stainless steel, the durability of the first and second engaging teeth 21, 31 will be substantially enhanced to prolong the service life span of the first and second rotor gears 20, 30. As it is mentioned above, if the first and second rotor gears 20, 30 are made of alloy, they must be frequently replaced for every three months. When the first and second rotor gears 20, 30 are made of stainless steel, they can be frequently replaced for every three years. Accordingly, there will be no or relatively less amount of residues formed during the rotational movements of the first and second gear motors 20, 30, wherein such amount of residues is under the safety level.

It is worth mentioning that since the pump device is substantially sealed by the sealing arrangement 40, the engagement between the first and the second rotor gears 20, 30 can be made less precise as compared to conventional pumping devices. This eventually reduces the manufacturing cost and the ultimate selling price of the present invention.

The sealing arrangement 40 further comprises a casing sealing element 43 provided between the first and second casing members 11, 12 to seal the pumping cavity 16 within the first and second casing members 12, 12 when the first and second casing members 11, 12 are coupled together.

The sealing arrangement 40 further has a retention slot 44 indent at the peripheral portion of the first casing member 11 to retain the casing sealing element 43 thereat so as to bias against the second casing member 12 when the first and second casing members 11, 12 are coupled together.

Likewise, the casing sealing element 43 is made of rubber material which is capable of preventing air and liquid from passing through the area sealed by the casing sealing element 43. Accordingly, the casing sealing element 43 is arranged to encircle a peripheral edge portion of the first and the second casing member 11, 12. Thus, the retention slot 44 is indently formed on the first casing member 11 at a position encircling a peripheral side edge portion thereof so as to prevent air and liquid leakage from the pumping cavity 16. When the pumping cavity 16 is sealed from ambient atmosphere, the efficiently of the pump device of the present invention can be substantially enhanced because the pumping action of the pump device is accomplished by rotation of the first and the second rotor gear 20, 30, which creates a vacuum effect in the pumping cavity 16 for sucking liquid from the storage tank 70 and the air from the surrounding environment.

The operation of the present invention is as follows: a user of the present invention will first put raw materials in liquid form into the storage tank 70. When the motor device 60 is operated, the first and the second rotor gears 20, 30 will be driven to rotate for creating a vacuum effect in the pumping cavity 16. As a result, the raw materials stored in the storage tank 70 will then be sucked into the pumping cavity 16 through the liquid inlet 13. Air will also be sucked into the pumping cavity 16 through the air inlet 14. The air will then mix with the raw materials in liquid form to become the mixture product, which is discharged through the mixture outlet 15 of the pump casing 10. The sealing arrangement 40 ensures substantial sealing of the pumping cavity 16 which reduces the manufacturing cost of other components of the pump device and provide efficient and effective vacuum of the pumping cavity 16.

One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting. It will thus be seen that the objects of the present invention have been fully and effectively accomplished. It embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims. 

1. A pump device for a frozen product machine, comprising: a pump casing having two inner side surfaces, a pumping cavity between said two inner side surfaces, a liquid inlet communicating said pumping cavity with an exterior of said pump device for allowing liquid mixture to be pumped into said pumping cavity through said liquid inlet, an air inlet communicating said pumping cavity for allowing intake of air through said air inlet to mix with said liquid mixture in said pumping cavity, and a mixture outlet communicated with said frozen product machine; first and second rotor gears being fitted in said pumping cavity in a rotatably movable manner, wherein said first and second rotor gears are driven to rotated to create a suction effect for pumping and mixing said liquid mixture with said air from said liquid inlet and said air inlet respectively to said mixture outlet so as to produce a mixture product; and a sealing arrangement comprising a plurality of sealing elements provided between two outer side surfaces of said first and second rotor gears and said inner side surfaces of said pump casing for ensuring said liquid mixture and said air being sealed and mixed within said pumping cavity through said first and second rotor gears and for preventing said first and second rotor gears from being direct-surface contact of said pump casing.
 2. The pump device, as recited in claim 1, wherein said first rotor gear are meshed with said second rotor gear to define a first chamber within said pumping cavity to communicate with said liquid inlet and a second chamber within said pumping cavity to communicate with said mixture outlet, wherein said pumping cavity is sealed by said sealing arrangement for ensuring said liquid mixture and said air being mixed from said first chamber to said second chamber to form said mixture product.
 3. The pump device, as recited in claim 1, wherein each of said sealing elements is made of elastic material adapted to be deformed to fit between said outer side surface of each of said first and second rotor gears and said corresponding inner side surface of said pump casing so as to create a sealing effect therebetween while enabling each of said rotor gears being rotated within said pumping cavity.
 4. The pump device, as recited in claim 2, wherein each of said sealing elements is made of elastic material adapted to be deformed to fit between said outer side surface of each of said first and second rotor gears and said corresponding inner side surface of said pump casing so as to create a sealing effect therebetween while enabling each of said rotor gears being rotated within said pumping cavity.
 5. The pump device, as recited in claim 1, wherein said sealing arrangement further has a plurality of sealing slots indent on said outer side surfaces of said first and second gear rotors respectively, wherein said sealing elements are retained at said sealing slots respectively to contact and seal with said inner side surfaces of said pump casing.
 6. The pump device, as recited in claim 2, wherein said sealing arrangement further has a plurality of sealing slots indent on said outer side surfaces of said first and second gear rotors respectively, wherein said sealing elements are retained at said sealing slots respectively to contact and seal with said inner side surfaces of said pump casing.
 7. The pump device, as recited in claim 4, wherein said sealing arrangement further has a plurality of sealing slots indent on said outer side surfaces of said first and second gear rotors respectively, wherein said sealing elements are retained at said sealing slots respectively to contact and seal with said inner side surfaces of said pump casing.
 8. The pump device, as recited in claim 1, wherein said first rotor gear, said second rotor gear, and said pump casing are made of stainless steel.
 9. The pump device, as recited in claim 4, wherein said first rotor gear, said second rotor gear, and said pump casing are made of stainless steel.
 10. The pump device, as recited in claim 7, wherein said first rotor gear, said second rotor gear, and said pump casing are made of stainless steel.
 11. The pump device, as recited in claim 1, wherein said first rotor gear comprises a plurality of first engaging teeth peripherally formed along an outer circumferential edge portion of said first rotor gear, while said second rotor gear comprises a plurality of second engaging teeth peripherally formed along an outer circumferential edge portion of said second rotor gear, wherein said first engaging teeth are meshed with said second engaging teeth for driving said second rotor gear to rotate.
 12. The pump device, as recited in claim 10, wherein said first rotor gear comprises a plurality of first engaging teeth peripherally formed along an outer circumferential edge portion of said first rotor gear, while said second rotor gear comprises a plurality of second engaging teeth peripherally formed along an outer circumferential edge portion of said second rotor gear, wherein said first engaging teeth are meshed with said second engaging teeth for driving said second rotor gear to rotate.
 13. The pump device, as recited in claim 1, wherein said pump casing comprises a first casing member and a second casing member detachably coupled with said first casing member to define said pumping cavity within said first and said second casing member and to define said inner side surfaces at said first and second casing members respectively.
 14. The pump device, as recited in claim 12, wherein said pump casing comprises a first casing member and a second casing member detachably coupled with said first casing member to define said pumping cavity within said first and said second casing member and to define said inner side surfaces at said first and second casing members respectively.
 15. The pump device, as recited in claim 13, wherein said sealing arrangement further comprises a casing sealing element provided between said first and second casing members to seal said pumping cavity within said first and second casing members when said first and second casing members are coupled together.
 16. The pump device, as recited in claim 14, wherein said sealing arrangement further comprises a casing sealing element provided between said first and second casing members to seal said pumping cavity within said first and second casing members when said first and second casing members are coupled together.
 17. A method of making frozen product, comprising the steps of: (a) feeding a liquid mixture and air into a pumping cavity of a pump casing through a liquid inlet and an air inlet thereof respectively; (b) driving two gear rotors to rotate within said pump casing for generating a suction effect to pump and mix said liquid mixture with said air to form a mixture product; (c) providing a sealing effect between two outer side surfaces of said first and second rotor gears and two inner side surfaces of said pump casing by a sealing arrangement for ensuring said liquid mixture and said air being sealed and mixed within said pumping cavity through said first and second rotor gears and for preventing said first and second rotor gears from being direct-surface contact of said pump casing; and (d) pumping out said mixture product out of said pumping cavity through a mixture outlet of said pump casing.
 18. The method, as recited in claim 17, wherein the step (b) further comprises the steps of: (b.1) defining a first chamber within said pumping cavity to communicate with said liquid inlet by meshing said first rotor gear with said second rotor gear, and (b.2) defining a second chamber within said pumping cavity to communicate with said mixture outlet, wherein said first and second chambers of said pumping cavity are sealed by said sealing arrangement for ensuring said liquid mixture and said air being mixed from said first chamber to said second chamber to form said mixture product.
 19. The method, as recited in claim 17, wherein the step (c) further comprises a step of providing a plurality of sealing elements at said outer side surfaces of said first and second rotor gears respectively to bias against said inner side surfaces of said pump casing so as to seal a clearance between said outer side surfaces of said first and second rotor gears and said inner side surfaces of said pump casing.
 20. The method, as recited in claim 18, wherein the step (c) further comprises a step of providing a plurality of sealing elements at said outer side surfaces of said first and second rotor gears respectively to bias against said inner side surfaces of said pump casing so as to seal a clearance between said outer side surfaces of said first and second rotor gears and said inner side surfaces of said pump casing.
 21. The method, as recited in claim 19, wherein each of said sealing elements is made of elastic material adapted to be deformed to fit between said outer side surface of each of said first and second rotor gears and said corresponding inner side surface of said pump casing so as to create a sealing effect therebetween while enabling each of said rotor gears being rotated within said pumping cavity.
 22. The method, as recited in claim 20, wherein each of said sealing elements is made of elastic material adapted to be deformed to fit between said outer side surface of each of said first and second rotor gears and said corresponding inner side surface of said pump casing so as to create a sealing effect therebetween while enabling each of said rotor gears being rotated within said pumping cavity.
 23. The method, as recited in claim 21, wherein the step (c.1) further comprises a step of configuring a plurality of sealing slots indent on said outer side surfaces of said first and second gear rotors respectively, wherein said sealing elements are retained at said sealing slots respectively to contact and seal with said inner side surfaces of said pump casing.
 24. The method, as recited in claim 22, wherein the step (c.1) further comprises a step of configuring a plurality of sealing slots indent on said outer side surfaces of said first and second gear rotors respectively, wherein said sealing elements are retained at said sealing slots respectively to contact and seal with said inner side surfaces of said pump casing.
 25. The method, as recited in claim 17, wherein said first rotor gear, said second rotor gear, and said pump casing are made of stainless steel.
 26. The method, as recited in claim 24, wherein said first rotor gear, said second rotor gear, and said pump casing are made of stainless steel.
 27. The method, as recited in claim 17, wherein, in the step (b), said second gear rotor is driven to rotate by a rotational movement of said first gear rotor that first engaging teeth of said first gear rotor are meshed with second engaging teeth of said second gear rotor.
 28. The method, as recited in claim 26, wherein, in the step (b), said second gear rotor is driven to rotate by a rotational movement of said first gear rotor that first engaging teeth of said first gear rotor are meshed with second engaging teeth of said second gear rotor.
 29. The method, as recited in claim 17, further comprising a step of configuring said pump casing to have a first casing member and a second casing member detachably coupled with said first casing member, wherein said pumping cavity is defined within said first and said second casing member and said inner side surfaces are defined at said first and second casing members respectively.
 30. The method, as recited in claim 28, further comprising a step of configuring said pump casing to have a first casing member and a second casing member detachably coupled with said first casing member, wherein said pumping cavity is defined within said first and said second casing member and said inner side surfaces are defined at said first and second casing members respectively.
 31. The method, as recited in claim 29, further comprising a step of providing a casing sealing element provided between said first and second casing members to seal said pumping cavity within said first and second casing members when said first and second casing members are coupled together.
 32. The method, as recited in claim 30, further comprising a step of providing a casing sealing element provided between said first and second casing members to seal said pumping cavity within said first and second casing members when said first and second casing members are coupled together. 